Presently, printed circuit assemblies (PCAs) are comprised of a substrate (e.g., PC board) with associated microcircuits. Typically, PCAs are used in conjunction with chassis structures to allow a large amount of processing ability to fit into a small space. In general, the chassis structure may contain a multiplicity of PCAs operating independently, in conjunction, or as a portion of a larger network. Often, the PCA is attached to the chassis type structure in conjunction with very specific standards. Typically, PCA attaching standards include, for example, the compact peripheral component interconnect (cPCI) standard, and the VersaModular Eurocard (VME) standard.
Typically, PCAs used in the chassis type structure fabricated to one of the above-mentioned standards (e.g., cPCI or VME) have indicator lights such as light-emitting diodes (LEDs) mounted on the printed circuit board (PCB). The LEDs are conventionally used to signal various states of the applications running on the PCA including, but not limited to: when the PCA is available for hot swapping, diagnostic states, and progress indicators. For example, the cPCI industry standard LED color for the hot swapping status of a PCA is blue. Therefore, if the light is on (or off, or blinking depending on the specification) the PCA is ready to be hot swapped. In addition to application state information such as indicating hot swapping status, LEDs may be used to indicate local area network (LAN) connectivity, connection speeds (e.g., 10 megabits, 100 megabits, 1000 megabits, etc.), power on or off, or the like.
Another utilization of the LED on a PCA is for identification. Specifically, if service personnel are working on a chassis and need to identify a specific PCA an operator can turn an LED on or off for a short period of time, thus allowing correct identification of the PCA.
Since the LED is mounted on the PCB, both visual and physical access to the LED (or LEDs) is normally limited. For example, in order for a user to see the LED, holes must be drilled through the bulkhead of the PCA. The LED may then shine through the hole allowing a user to have visual feedback with regard to the status of the PCA. Sometimes, a light diffusing pipe is used in conjunction with the hole in the bulkhead of the PCA to allow a better view of the LED.
One deleterious effect of drilling a hole through the bulkhead of a PCA in order to observe the LED is the lack of uniformity between LED locations per PCA. For example, there is no cPCI industry standard for the location of the LED(s). Therefore, whoever designs the system (or PCA) must also establish the location(s) of the LED(s), design the bulkhead with the correct hole location(s), and choose whether or not to use a light diffusing pipe (or pipes) in conjunction with the LED(s).
In addition to the custom bulkhead requirements mentioned above, since there is no industry standard LED location, users (e.g., administrators and service personnel) can never be sure of the location of the LED with respect to the bulkhead. Therefore, a user may believe the blue LED is off and the PCA is ready for hot swapping, but in fact, they may be looking through the wrong hole or at the wrong LED. In such a case, the PCA may be removed prematurely and damage to components within the PCA may occur.
Another problem with the use of LEDs on a PCB is the amount of room they require. For example, not only does the LED take up space on the PCB but other connectors, cables, indicators, and the like, must be carefully placed around the LED and the viewing hole for the LED to ensure there is no blockage of the light from the LED to the bulkhead. Moreover, the bulkhead of the PCA also has limited room. Therefore, drilling a hole (or holes) in the bulkhead (in order to establish a viewing window for the LED) leaves less room for connectors, labels, communication ports, and the like.
Furthermore, PCAs used in the chassis type structure fabricated to one of the above-mentioned standards (e.g., cPCI or VME) have ejector latches that are utilized to provide attachment of the PCA with the chassis. In order to ensure correct attachment of the PCA with the chassis has occurred, an engaged/disengaged circuit is integrated with the ejector latch. Therefore, when the PCA is properly installed, the ejector latch circuit is closed and operation of the PCA may commence. However, if the PCA is incorrectly installed, then the ejector latch circuit will remain open and operation of the PCA may not commence. In addition, when an operational PCA is prepared for removal from the chassis, the ejector latches are disengaged. The disengagement of the ejector latch opens the ejector latch circuit and allows the PCB to prepare for removal from the chassis. For example, when the ejector latches are disengaged, the PCB may begin the process of shutting down in preparation for removal from the system.
In general, during the assembly of a PCA, the ejector latch is mounted partially to a bulkhead, and then the PCB is attached to the ejector latch. The PCB is then screwed into position with respect to both the bulkhead and the ejector latch. A pigtail from the ejector latch is then plugged into the PCB. On average, the length of the pigtail is one inch, therefore, the plug in location on the PCB must be somewhat close to both the ejector latch and the bulkhead.
One deleterious effect of utilizing the above stated pigtail to connect the ejector latch with the PCB is the requirement of plugging in the pigtail before inserting the PCA into the chassis. For example, during shipping of an assembled PCA the connection between the ejector latch and the PCB may become loose. If a user is unaware of the disconnection, the PCA mounted on the chassis may not operate due to a false open signal generated by the PCB. In such a condition, the user would be required to troubleshoot the PCA or hire a technician to troubleshoot the PCA in order to resolve the issue.
Another problem with the pigtail connector is the wear and tear of the wires in the pigtail. For example, the wear and tear associated with insertion or removal of the PCA from the chassis. Specifically, the wires may rub against other structures on the chassis (e.g., card guides, framework, other PCA's, etc.) or the PCA itself (e.g., locator pin, etc.) resulting in disconnection of the male end of the connector from the female end. Furthermore, the wear and tear on the wires may result in a short circuit between the wires resulting in a false open or closed ejector latch status. Additionally, the wear and tear may result in complete separation of a wire in the connector.
In addition to the disconnection problems mentioned above, there is no cPCI industry standard PCB plug-in location. That is, PCB designers may place the PCB connector for the ejector latch pigtail in a range of locations. Therefore, the expense and time or further custom manufacturing is required. For example, the designer may have a range of one-inch diameter in which the placement of the PCB connector for the ejector latch pigtail. Moreover, if a designer uses or designs a PCB for use with an ejector latch having a two-inch pigtail, then a user may be further limited to the type of ejector latches that may be used with a specific PCB.
Thus, the utilization of ejector latch connectors is non-standard, time-consuming, and lacks the desired “Design for Manufacturability.”